I'm so sorry for the pain and discomfort you've experienced for so long and at such a young age. You do not sound like a hypochondriac at all, you sound like someone who has had a craniotomy! When I had my surgery, I had to sign off on a laundry list of possible side effects, one of which was permanent headaches. The others--facial paralysis, permanent balance issues, death--were all frightening. Even benign tumors can grow, so the younger you are, the more important is removal; so if you're regretting your decision to have it out, don't. Otherwise you could be dead.
I hope you've made an appointment with your original neurosurgeon plus one more as a second opinion. There might be something going on with scar tissue that makes your neck sore. Hopefully someone else on the board may have another suggestion, but only a doctor who has all your information and your head in front of him can really help.